U. S. DEPARTMENT OF AGRICULTURE. 
BUREAU OF PLANT INDUSTRY - -BULLETIN No. 34 



b. T. GALLCVV 



0! I'd'-IJUL. 



SILKWORM FOOD PLANTS 



CULTIVATION AND PROPAGATION. 



GEORGE W. OLIVEK, Expert, 

SEED AND PLANT INTRODUCTION AND DISTRIBUTION. 



Is.s:M;n jANrARv 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1903. 




Glass. 
Book. 



^) 



34, Bureau of Plant Industry, U. S Drpt. of Agriculture^ 



Frontispiece. 




U. S. DEPARTMENT OF AGRICULTURE. 
BUREAU OF PLANT INDUSTRY— BULLETIN No. 34. 

B. T. GALLOWAY, Chiff of Bureau. 



SILKWORM FOOD PLANTS 

CULTIVATION AND PROPAGATION. 



GEORGE W. OLIVEK, Expeet, 

SEED AND PLANT INTRODUCTION AND DISTRIBUTION. 



[ssuED January 15, 1903. 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1903. 






MAR 31 1903 
D. ot 0. 



millR OF TRAXSMIHAL 



U. S. Department of Agriculture, 

Bureau of Plant Industry, 

Office of the Chief, 
WaHhingion, D. ('., Oetoher 27, 1002. 
Sir: I have the honor to transmit herewith a paper entitled "Silk- 
worm Food Plants: Cultivation and Propagation,'' by George W. 
Oliver, Expert, Seed and Plant Introduction and Distril)utio''n, and 
respectfully recommend its publication as a bulletin of this Bureau. 

The paper has been prepared at the request of Dr. L. O. Howard, 
under whose direction the funds appropriated at the last session of 
Congress for an investigation into the subject of silk culture in this 
country are expended. Dr. Howard has made a number of sug- 
gestions in regard to the scope and character of the paper, and has 
furnished the illustration used as a frontispiece, selected from a large 
number of photographs taken by him during the past summer while 
investigating the silk-cultural industry in Italy and other countries. 
Respectfully. 

B. T. Galloway, 



Hon. James Wilson, 

Secretary of AgrleuUure. 



Chief of Bureau. 



CO XT l:\TS. 

Page. 

Introduction 7 

Methods of reproduction ^ 

Propagation by cuttings 9 

Summer cuttings 9 

Winter cuttings 10 

The cutting 10 

Preparations for planting cuttings 10 

Indoor spring cuttings 11 

Propagation by seeds 11 

Crrafting and budding l^^ 

Root grafting 13 

Scion or sprig budding 1-t 

Shield budding 15 

Raising stocks for grafting and l)udding Itj 

Soil '. Iti 

Planting I'l 

Pruning 1~ 

Description of ))lates 20 



ILLUSTRATIOXS. 



rase. 

Mnlhcrrv tn-es and leaf <ratlierers, Lomhanly, Italy Fronti.^piece. 

Platk I. Branch of the white mulberry, Mnrux (ilha, with larire undivided 

leaves 20 

II. IJranch (if the white mulberry, Morns alha, with divided leaves 20 

III. -An ornamental variety of mulberry, Morns (tiba, yariety nmosa 20 

IV. Leaves of seedling Russian mulberry, Morns alba, variety tatarlca.. 20 
V. The native red mulberry, MoritK rubra 20 

VI. Taper nudberry, Broummeiia jiapiirifcrn. A. — Leaf from old tree. 

H. — Leaf from 2-year-old seedling. C. — Twig with female flowers. 20 

VI I . Tlic Persian or Ijlack mulberry, M^orns )ii(/ra 20 

VIIL Osage orange, To.viilon poniifemm. Leav(>s. fruit, and l)ark 20 



IX. Summer cuttings of the white inullu'riy, witli leaves shortened 

X. Winter cuttings of l-year-old shnots nf the white mulberry, ready 

for planting 

XL Root grafting the nudlterry. A and 15. — Scions litted on stocks, 
ready to l)e tied. C. — Stock and scion wraiijied and ready to be 

planted 

XIL Scion or sprig budding. A and B. — Scions prepared for inserting. 
C. — Stock with bark raised, ready for scion. D. — Scion in posi- 
tion, ready to be wrapped. E. — Stock with scion held in place 

by wrapping. F. — Stock waxed to exclude air and moisture 

6 



S. p. I. D.— 30 



SILKWOKM FOOD PLANTS: ( ULTIVATION AM) 
PROPAGATION. 



INTRODUCTION. 

There is a small family of plants t-losely allied to each other, a few 
of which supply the silkworm with food. This family is called 
2Ioraceie. There are three crenera of trees in the ofroup — Momx, the 
mulberry (Pis. I. II. Ill, IV^, V. and VII); To.njJon, the Osage orange 
(PI. VIII), and Bronxxonefia, the paper mulberry (Pi. VI). The last 
named, being unsuitable for silkworm food, will not again b(> referred 
to here. 

The Osage orange provides palatalile food for the silkworm, and if 
the worms were free to select the leaves foi- themselves the tree would 
be satisfactory; but the leaves are selected for them often with bad 
results, for the young and immature leaves have a tendency to sicken 
the worms. Ignorance of this fact renders the use of the Osage 
orange dangerous. 

Of the mulberry there are manv so-called species and a great many 
varieties, but there are only one or two species and a few varieties 
which are of importance in silkworm propagation. Chief among 
these for producing silkworm food is the white mulberry, Morxx alba 
(PI. I). This is thought by some to be a native of China. It has 
long been known that the white mulberry and its varieties are hardy 
over a large area of the United States. 

The uninitiated should not be left to their own devices in growing 
mulberry trees, especially if the enterprise is to be an extensive one, 
for if failure results, silkworm propagation in the particular section 
of the country where the experiment is conducted wdl receive a seri- 
ous setback. 

It is not the purpose of this paper to discuss the question of the 
most suitable varieties of the white luulberry, as this could only be 
done from a European point of view. Bureau, in his monograph, 
describes :27 varieties of the white mulberry alone. In Italy, silk- 
worm gi'owers favor MoruM alba, variety morttti, and forms raised 
from it. France and Spain have each its favorite kinds. Japan has 



8 SILKWOEM FOOD PLANTS. 

close upon 1()(> forms, one or two of which would probably answer all 
purposes, while most of the silkworms reared in China are said to be 
fed upon Moran muItu-auU.s. This mulberr\- was largely planted in 
the United States many years ago. Few, if any, of the original trees 
remain, but specimens which are thought to be wild seedlings of these 
are yery plentiful in the Southern States. These trees are thoroughly 
acclimated and free from disease. It is therefore probable that there 
is now in the United States an abundant supply of material for propa- 
gating purposes, at least. 

It is intended to show in these pages how the mull^erry may be prop- 
agated and grown so as to proyide the maximum amount of leayes 
for the food supph^ of the worms. The white mulberry, under good 
cultiyation, is a low-growing tree, seldom attaining a greater height 
than 2.5 or 30 feet. It will reach this height in a comparatively few 
years after planting. Although it will live to a good old age, its 
growth, like that of most other trees, is most rapid when young. As 
the trees attain their full height they become stocky and make a mul- 
titude of small growths, from Avhich flowers and fruit are produced. 
The fruit, which is usually abundant, is not a favorite in this country, 
being generally considered too sweet and insipid. In shape it may be 
said to resemble more or less that of an elongated l>lackberry. In the 
vicinity of Washington the trees flower about the middle of May and 
ri})en their fruit during June. 

METHODS OF REPRODUCTION. 

The usual methods of propagation in use for fruit trees are emploA'ed 
with varying degrees of success in the case of the mulberry. These 
methods consist of budding, grafting, layering, cuttings, and seeds. 

(i rafting and budding are by far the most expensive methods, and it is 
doubtful if the results justify their use, so far as raising mulberry trees 
is concerned. Part of the work connected with Imdding and grafting 
consists in raising stocks, which are seldom large enough for use until 
they are two j-ears old. At this age, the })uds or grafts are inserted, 
and tlien troubles previously undreamed of present themselves to the 
inexperienced cultivator. Were the mulberr}^ tree as easily managed 
so far as budding or grafting is concerned as is the i)each, the use of 
th(\s(^ methods would be feasible, but unfortunateh' the mulberry is 
far fiom being an easy subject in this respect, and a few failures are 
apt to produce disappointment and disgust. It will frequently happen 
that old trees must either be removed or desirable varieties worked 
on them; budding or grafting may be resorted to in such cases. 

Layering consists in bending down a portion of a branch so that its 
stem after being notched may take root in the ground while still 
attached to the parent tree. It is a cumbersome method, however. 



METHODS OF KEPRODUCTIOX. 9 

Althoutih good-sized plants c-aii be raised in a short time by its use, it 
is seldom employed when any other method will produce the same 
results. 

Raising young trees from cuttings of the 1-year-old ripened wood 
is a method which requires but little skill. As with budding and 
grafting, this method is instrumental in perpetuating varieties, as 
ever}' rooted cutting will eventually be a reproduction of the tree from 
which it was taken. This is not the case with plants raised from seeds, 
which always vary considerably from the parent. For this reason some 
mulberry growers in Europe object to the seed method. Some of 
the seedlings, even from a single parent tree, will vary greatly in the 
value of the leaves for feeding purposes. Some will be thin in texture 
and lacking in the necessary chemical constituents; some, very hair}^; 
others thick, smooth, and in ever}- way desirable. However, experi- 
enced mulberry growers can readih' tell the value of a seedling tree 
for feeding purposes, and it is therefore possible to make a selection 
in this respect without nuich loss. 

rROPA(;ATioN rn' cuttings. 

SIMMKK (TTTINdS. 

In any group of seedlings there will always be found individuals the 
leaves of which possess great adaptal)ility for feeding purposes. These 
should certainly be propagated to perp(»tuate this desirable character- 
istic. Propagation should be started after the seedlings have made 
considerable growth in order to insure a good suppl}' of wood. These 
plants should be increased by cuttings during the sunnner months. At 
this season it is advisable to retain some of tne leaves on the cutting 
and give treatment which will prevent shriveling during the process 
of rooting. The cuttings shoidd be made from wood as ripe as possible: 
the leaves, besides being well matured, should be healthy and free from 
noxious insects. During Juh' the lower parts of the current season's 
shoots will ])e found in good condition for propagating. 

Trim the cuttings similarly to those shown in PI. IX. At least 
two leaves shortened to one-half their length should be allowed to 
remain on the cutting. When placed in the propagating bed, the slips 
should be inserted in the sand in a direction sloping from the opei-atoi'. 
Good results will follow if a cool propagating house is used, with clean 
sand as the rooting medium. When a propagating house is not avail- 
al)le, a wide frame provided with sash will answer the purpose. The 
frame should face north, and if in the shade of trees, so much the bet- 
ter. The sash should be kept closed, so that a humid atmosphere may 
be maintained until the cuttings take root. After they have made 
a considerable quantity of roots in the sand the}' should be transferred 



10 



SILKWOKM FOOD PLANTS. 



to beds in the open. The beds should be 5 feet wide. Place the 
rooted cuttings al)out inches apart each wa}^ and water copiousl}^ 
until established, when they must be freely- exposed to air and sunshine. 



AVIXTEK (ITTINC 



The enttln(i.—'Y\\Q principal supply of plants may ])e secured l)y 
propao-ating- from cuttings, which should be made from dormant wood 
taken from the trees just after the leaves have fallen. 

In no case should the cutting wood be less in diameter than a quarter 
of an inch. The cuttings (PI. X) should be about 10 inches in length, mak- 
ing the upper cut about one-half inch above a bud. The position of the 
lower cut is immaterial. The cuttings should now be tied in bundles 
of fifty and either stored for the winter or be inunediately put out 
where they are to root. ^Vhere the winters are not too severe, or in 
the Eastern States south of the thirty- ninth parallel, they should be 
put in the ground during autumn. North of this it will be found 
best to keep them undcu- cover until the ground is in a condition to be 
worked in early spring. If they are kept even for a short time in a 
dry place, they will lose their sap and ])ecome shriveled. Therefore 
they should be buried in moderately moist sand or sand and ashes. 
Under such conditions a good callus will have formed aiouiid the 
lower cut surface before the time arrives when they an^ to be ])ut in 
the open. If sphagiuun moss be easily procural)le, it can l)c used very 
successfully as. a substitute for sand or ashes; but in Ihis case the 
bundles of cuttings should be smullei- and they should be ])lac(Ml with 
the buds pointing upward, the moss to b.. packed tightly around them, 
with the top part uncovered. This is an excellent nieth(.d foi' induc- 
ing the formation of a good callus. 

Preparat'wnHf(>rj>I,iiiin,,i <iiffn,<is. WWum^ to putting the cut- 
tings in the open the soil should b.' jjlowed deeply, then'harrowed 
and rolled until well pulverized. A furrow is made With a spade to a 
sufficient depth, a little sand placed in the ])ottom. and the lower ends 
of the cuttings placed on top. Fill in the soil to half the depth of the 
furrow, firm well with the feet, then till in the remainder of the soil, 
leaving only enough of the cutting exjjosed to view to keep the top 
bud from being covered. Where there is danger of hard freezing 
weather after fall planting, cover the surface with rough stable litter 
or dead leaves, this covering to be removed before the ])uds begin to 
swell during the latter part of March. 

The rows of cuttings can be arranged in beds of any convenient 
width, leaving spaces between the beds; this arrangement will facili- 
tate covering, watering, and hand-weeding. If plentv of good ground 
IS available, enough space should be left l)etween the rows to permit 
of horse cultivation. During the summer the plants should be gone 
over several times and all superfluous shoots removed, leavin<.- onlv 



CUTTINGS AND SEEDS. 11 

one shoot to each plant. If hirge enough, the vooted cuttino-.< should 
be removed to nursery rows the followinj^ fall. In no case should the 
plants be removed from the cutting beds to permanent locations. 

If the plants make sufficient growth the first season, they should l)e 
severely cut back; otherwise the operation should be deferred until the 
following season. The length of stem to remain as the future trunk 
must be regulated according to w^hether a dwarf or tall specimen is 
wanted. It must be taken into consideration that the leaves are much 
more easily gathered from dwarf trees than from tall ones; in fact, 
they are more easily managed, not only so far as leaf gathering is 
concerned, but also in pruning and in keeping noxious insects and 
fungus diseases under control. The leaves on a tall tree are not all 
developed alike; those on the side fully exposed to the sun will 
naturally be in perfect condition, while on the opposite side they are 
softer and pr()ba])ly not so well adapted to the purpose for which they 
are intended, ^Medium-sized trees are therefore preferable for all 
purposes. 

INDOOK SPin.Nc; ( rTTIN(iS. 

Another method of propagation from cuttings, and a very success- 
ful one, consists in selecting medium-sized shoots about the beginning 
of November. These, before being made into cuttings, are sorted into 
bundles of different lengths, tied, and heeled in ashes or sand, or in a 
mixture of both, and protected by a frame having a northern exposure. 
During the winter they are taken out and cut into lengths of about 
5 inches. These are tied in bundles and buried in moist sand or 
moss. In early spring the}' are untied and put (juite thickly in a 
propagating bed having a mild bottom heat, wher(^ they will root 
rapidly. When such a bed is lacking, wooden fiats al)out -t inches 
deep may l)e used for the reception of the cuttings; l)ut they nuist 
have the protection of a frame covered with sash. If a little loamy 
soil is placed in the bottom of the fiats the cuttings will remain in good 
condition for a considerable tim<^ after rooting and until a favorable 
opportunity arrives for planting them out in nursery rows. If those 
rooted indoors are given plenty of air after being rooted in the bed, 
they can ])e transferred to the open ground with safety during dull 
weather. 

PROVACATKW BY SEKDS. 

The most convenient and rapid method of propagation is undoubtedlv 
from seeds, as they are quick to germinate and the seedlings make 
growth about as rapidly as plants raised from cuttings. Seeds sown 
shortly after being harvested will germinate in a few days. If kept 
over winter and sown in early spring, the seedlings will appear within 
fourteen days. When the seed is spring sown, the seedlings will, if 
the weather be propitious, attain a height of from 12 to 18 inches in 



12 SILKWORM FOOD PLANTS. 

one year; but during- dry seasons they will only grow from t! to 12 
inches. Seedlings from seeds sown immediately after the fruit ripens 
are always small at the end of the season, but they produce strong 
plants the season following. 

Seed is usually produced in great abundance by nearly all of the 
species and their varieties. The mulberry, like the strawberr}^ black- 
berry, and raspberr}', does not ripen all of its fruit at one time; con- 
sequently several g-athering-s are necessary before a crop is harvested 
from any one tree. The earliest fruits can be gathered immediately 
after thev are ripe and the seed sown if desired. It should be remem- 
bered that seedlings thus raised have comparatively little time to make 
their growth; therefore, every day counts. 

In gathering- the fruit, it will be found easiest to shake the tree and 
pick the fruits from the ground. To remove the seeds from the sur- 
rounding pulp, put the fruit into a large ])ucket or tub and squeeze 
with the hands until it becomes a jelly-like mass. Add water and stir 
well until the contents are thinned suthcientl} to allow the seeds to 
sink to the bottom. The remaining- material can ]>e poured oS. The 
seeds should be exposed to the air until dry. If it is desired to sprout 
them the same sununer, they should be sown in l)cds in the open, the 
soil of which sliould previously be well worked by deep plowing and 
gone over several times with a harrow and a roller. When the soil is 
sufficiently pulverized the ground should be marked oft' into ])eds 5 
feet wide and of any convenient length . leaving a space of 2 feet 
between the beds. To prevent washing of the soil and also to mini- 
mize the evil eftects of drying winds, drive some stout stakes into the 
ground along the sides and ends of the beds, and to these nail eight or 
twelve-inch boards. The surface of the bed should be leveled and all 
stones and roots of plants removed with a hand rake. 

Sow the seeds broadcast, taking- care not to sow them too thick, as 
there is a danger of the seedlings crowding each other. Crowding 
produces weak plants, because even the best soil is capable of sup- 
porting only a certain numl)er of plants to the scjuarc foot. Press 
the seeds into the soil with the back part of a spade and cover lightly 
with soil screened through a quartei--inch sieve. 

In order to have the best results, the seed l)eds should not be exposed 
to the sun until a considerable time has elapsed after germination. 
This condition may be arranged as follows: Procure some pieces of 2 
by 3-inch scantling; place two of the pieces parallel to each other 5^ 
feet apart. Nail laths from one to the other, using the 2-inch surface 
in which to drive the nails. Leave 1-inch spaces between the laths. 
The slats are put lengthwise over the beds, and can be used with or 
without the side boards. Over the slats spread archangel mats, or can- 
vas, until germination takes place; these coverings should be fre- 
quently dampened. After the seedlings show above the ground, the 



GRAFTING AND BUDDING. 13 

cloth covering-s are to be kept on during the hottest part of tlie day 
onh', and when the first true leaf appears the}' ma,y be removed alto- 
gether and the shade necessary thereafter supplied by the lath slats. 
Water must be supplied if the soil needs it. With spring-sown seed, 
the coverings over the lath slats ma}' be dispensed with, but the sur- 
face of the bed should not be allowed to become dry until the seedlings 
are large enough to take care of themselves. 

CRAFTING AND BUDDING. 

In Italy and other silk-raising countries it is claimed that the leaves 
of trees raised from cuttings and seeds are superior for silk produc- 
tion, but that the quantity of leaves produced by trees so propagated 
is only about one-half the bulk of those from grafted or budded trees. 
Therefore, to produce a large quantity', grafting and budding methods 
of propagation are practiced to a great extent. Before the beginner 
undertakes these expensive methods of propagation in the United 
States, however, he should consider that land rentals are high in 
Europe and that land is cheap in the United States; therefore the 
American can afford to grow more trees l)y the methods which are 
instrumental in giving the best grades of silk. This is an important 
point to consider, and the writer is inclined to the belief that in the 
propagation of plants giving the highest grades of silk there will be 
little danger of a scarcity of material, as the mulberry thrives as well, 
if not better, in most parts of the I'nited States as anywhere in 
Europe. 

For those who decide to try propagating by grafting and budding 
two of the most successful methods of performing the operation are 
here described. 

ROOT (;kaftin<;. 

This is performed in February and March. The stoi-ks. which are 
two-year-old seedlings of the Russian mulberry (J/o/v^s tdha^ variety 
tatarica), should show a diameter of at least three-eighths of an inch 
to give a satisfactory union. The stocks should be lifted in the fall 
and "heeled in" out of the reach of frost. The scions should be cut 
while in a dormant state and buried in damp sand in a protected place. 

In the latter part of February the work of root grafting (PI. XI) may 
be started. The preparatory work consists in securing a quantity of 
strong tidy cotton, and of grafting wax made of beeswax two parts, 
of resin two parts, and of mutton tallow one part. Put the ingredi- 
ents in a small tin l)ucket, place on a hot stove, and when melted drop 
in one or more balls of the cotton, allowing them to remain in the 
melted wax for live minutes; remove with a pointed stick. When 
cool they are read}- for use. Procure a deep box in which place the 
stocks, keeping them covered with a dampened sack; another box 



14 SILKWORM FOOD PLANTS. 

should be provided for the .scions .similarly protected, and a third one 
for the grafted roots. These precautions are necessar3', as a little 
exposure to dr}- air is alwa3"S detrimental. 

In beo-inning work with the stocks sever the top from the root at the 
collar; this can be done best with a pair of pruning- shears. Take a 
scion at least 8 inches long and attach by the tongue method, as shown 
in PL XI. Select stocks and scions of as nearly the same diameter as 
possible; make a slanting cut at the bottom of the .scion and a similar 
cut at the top of the stock. In the ca.se of the scion, make an upward 
incision at a point about one-third of the length of the cut surface 
from the base; this will form a tongue. Next make a corresponding 
incision downward near the top of the .slanting cut on the stock. The 
idea is to have the tongue of the scion take the place which the knife 
blade occupies when making the incision in the stock. When the two 
parts are neatly fitted so that the bark of stock and of scion come 
neatly together at one side, or at both if possible, bind lirmly with 
the waxed cotton. This material should be used in preference to raffia, 
because when the grafted stock is buried in the ground, raffia would 
be certain to rot before the union took place, while cotton will remain 
in good condition for a long time. 

After the fitting and tying have been done, the grafted stocks should 
be tied in bundles of twenty-five, the first tie to be made rather firmly 
near the upper part of the scions; secure them again near the base of 
the scions, but not as firmly as before. Care must be taken so as not 
to displace the fitted parts. The bundles should now be buried in sand 
in a frame or other protected place until planting time arrives. The 
grafted stocks should be planted out just as soon as the condition of the 
.soil will permit. Plant them deep enough .so that only the top bud is 
expo.sed to the light. 

The subsequent treatment is in all respects similar to that given for 
cuttings. Mark the kinds, with the dates of grafting and planting, on 
large labels which will not l)e easily displaced. 

.SCION OR SPRIG BUDDING. 

Scion or sprig budding, as shown in PL XII, is perhaps the most 
successful and easiest to accomplish of all methods. It is practiced on 
stocks which have not been transplanted for at least one 3^ear previous 
to the time when it is desired to bud. The stocks should be larger 
than those used for root grafting. The most desirable time for the 
operation is in spring, when the bark lifts easih^; this will necessarily 
be after the stocks come into leaf. The scions must be selected from 
shoots of the previous season's growth, short and stocky, with two 
buds present (PL XII, A and B). They should be cut from the parent 
plants in the fall and kept dormant until the opportune moment arrives 
when the stock plants are in a receptive condition. 



SCION AND SHIELD BUDDING. 15 

In preparing the stock for the scion the preliminary work is siinihir 
to that in shield budding the peach, cherry, or rose. At a point a little 
above the collar of the stock a transverse cut is made through the 
bark for a distance of half an inch or more around the stem (PI. XII, C.) 
This is followed by a longitudinal cut, beginning in the middle of the 
first cut and extending downward for about an inch. Prize up the 
bark at each side of the long cut (PI. XII, C) and it is ready for the scion, 
which is prepared for insertion by making an oblique cut through the 
base, so as to leave a cut surface about an inch long (PI. XII, A and B). 
The scion is then fitted in place so that its cut surface is neatly placed 
against the wood of the stock (PI. XII. D) laid bare by the raising of 
the bark. The next operation is shown in PI. XII, E, and consists in 
tying the parts together so that they will l)e held firmly while the 
union is taking place. In order to exclude air and moisture, grafting- 
wax or clay should be applied, as shown in PI. XII, F. 

Within two weeks from the time of l)udding. th(> union will l)e 
effected, if everything has gone well. The ligature should not be 
removed, however, until there is danger of its cutting into the bark. 
The most essential part of the subsequent treatment consists in head- 
ing back the stock, so that the future head of the tree will be formed 
by the growth of the scion, and to do this successfulh' good judgment 
must be exercised. Cut oft' onlv a part at first, leaving some foliage 
on the stock until the buds on the scion ])egin to push, when that part 
of the stock above the union should ))e i-emovod with a sharp knife. 
Cover the wound thus made with grafting wax. 

(SHIELD IUni)IN(;. 

The shield SA'stem of Imdding may be used, but only in the spring, 
as the mulberry does not take kindly to shield buds inserted during 
the season suitable for most of our fruit trees. 

Shield budding consists in selecting a stock, either a l)ranch or st(Mn. 
from which the bark slips readily. In raising the bark of the stock 
for the reception of the bud, the work is similar to that described for 
scion or sprig budding. The bud is usually selected from dormant 
wood kept over winter in ashes or sand; but for this there exists no 
necessity, because there is always present an abundance of dormant buds 
on a growing plant, and these answer the purpose much better than 
buds from dormant wood. To remove them, with a sharp knife make 
an incision in the stem about five-eighths of an inch l)elow the bud; 
bring the ))lade up under the bud, severing a section of bark three- 
eighths of an inch in width, with the bud in the center; bring the 
blade out a little above the Inid. If this operation is neatly performed 
the l)ud will require no further trimming before being inserted under 
the bark of the stock. The bark of the stock is then firmly bound 
over that of the bud and the parts kept in position with raSia. No 



1(> SILKWORM FOOD PLANTS. 

waxing- is necessary. Tlie union should take place within fifteen days, 
after which the lig-ature should l)e loosened or removed as proves 
necessary. 

RAIfSIN(i stocks; for (iRAFTIX(; AND BrDDIXG. 

In grafting and budding irom any particuhir variety which it is 
desired to perpetuate, the Russian mulberry, Jlorns a/ha, variety 
iatai'ica, is the one used as stocks. It is of a robust-growing nature 
and has been found well adapted to the soils and climates of all the 
agricultural belts of the United States. It is this variety that is so 
much used in the West and Northwest for hedges, as it is the hardiest 
of all the nmlberries. 

Stocks are best raised from seeds, and a supply for this purpose 
should be obtained from a reliable source, to avoid unnecessarv delay 
and disappointment. The sowing and the subsequent management of 
the seedlings are the same with stocks as with seedlings for general 
planting, except that when planted in nursery rows they should l)e 
placed about a foot apart, so as to give an al)undance of space for the 
operator to work. 

SOIL. 

So far as has been ascertained, the mulljcrry is not particular as to 
the character of the soil. It seemingly grows equally well in a great 
variety of well-drained soils. Even in sandy and gravelly situations 
it holds its own. In shallow soils over hardpan the mulberry thrives 
after most of our fruit and ornamental trees have given up the 
struggle. Under the same conditions the Per:?ian mulberrj^ has been 
found to fruit abimdantly. 

Notwithstanding its behavior under what would be supposed adverse 
conditions, there are few plants which respond more vigorously to 
applications of manure. In Japan it has recently been shown that by 
linnng alone the percentage of fiber in the leaves decreased very per- 
ceptibly. Again, by liming and also manuring with sodium nitrate 
and calcium sulphate a still further reduction in the fiber was appar- 
ent. The trees operated on were \\ meters (5 feet) high. Each tree 
was treated with 500 grams (1.1 lbs.) of lime, -iOo grams (.9 lb.) of sodium 
nitrate, and 200 grams (.-1:4 lb.) of calcium sulphate. How the cater- 
pillars fared as a result of this change in the composition of the leaves 
is not stated. 

PLANTING. 

This all-important operation may be performed either in the fall or 
spring. After the leaves have fallen or are matured, no delay should 
occur in transplanting to permanent positions. When this period is 
selected, it gives good opportunities for the formation of new roots. 



PLANTING AND PRUNING. 17 

III s])rino- the trees may l)e tnm.splanted any time after the iiround is 
in a workable condition and up to the period when the buds are al)out 
to })urst into growth. Spaces intended to l>e phiiited shoukl be deeply 
worked beforehand by plowing- and harrowing, and after planting the 
weeds should be kept down. 

The distance between the trees should not be less than 10 feet in the 
rows, and the rows should be the same distance apart. If the field 
devoted to the trees is more than -1 or 8 acres in extent, wider spaces 
should be left at intervals for wagons, etc. It is certain that trees 
planted 10 feet apart will eventually occupy all the space; ))ut when 
there is danger of their becoming too much crowded, enough of 
the plants may be rooted out and l)urii('(l to allow the remainder 
abundant space to de\-elop. If this is done, those which are to remain 
permanently should be trained accordingly. The above arrangement 
is the best for trees nearly all the branches of wdiich can l)e reached 
fi'om the ground, not only for pruning, but also for leaf gathering. 

In planting trees similar precautions should })e taken to those in the 
case of ordinary forest trees; that is, not to allow the roots to become 
in the least dry from the time they are lifted from the nursery rows 
until i)lanted in the Held. As soon as they are lifted the roots should 
be dipped in a mixture of soil and water and kept covered until })laiited, 
so that the}' will not become dry. If the ground is naturally hard and 
the soil is poor, dig large holes, even for very young trees, as they grow 
rapidly and should be encouraged to make good, stout growths from 
the beginning. Put some good soil in the hole, spread out the roots 
on this, and cover with several inches of tine soil before firming with 
the feet. Allow the roots to be about the same depth in the hole as 
the}' were in the nurser}- rows. Prune back the growth of young trees 
one-half in the fall, and if necessary cut back to strong buds in early 
spring. 

PRUNING. 

The pruning of the trees presents no special difficulties so long as it 
is done early enough in the season to avoid late growth, which, if 
caught by cold weather before ripening, will perish during the winter. 
The principal pruning should be done in winter and should consist of 
shortening back strong growths so as to form a low, spreading tree. 
Keep the central part of the tree as free of growth as possil)le, to admit 
light and air. 

After the first cutting back, select three or more of the strong- 
shoots to form the principal branches. If they are strong and show 
a disposition to grow upright, they may be kept apart b}'^ using three 
sticks tied in the shape of a triangle; place these in the center of 
the tree and tie the branches to them until they grow in the desired 

11805— No. 34—02 2 



18 8ILKW0KM FOOD PLANTS. 

direction. By careful attention to cutting- out the undesirable growths 
the tree can be made to assume any desired shape. 

In gathering- the leaves always allow enough to remain on the tree 
to insure its perfect health. If some of the trees show signs of fail- 
ing- vigor as a result of excessive leaf gathering, it is advisable to 
allow them to grow for a season without picking, and b}' early prun- 
ing out of unnecessary growth perinit those growths which are desir- 
able to become ripened. 



P ] . A T E S 



DESCRIPTION OF PLATES. 

Froxtispikce. — ()1<1 niul})erry trees, showiii'/ Italian inethoil of pruninij;, witli a tiroup 
nf eml)ryo silk <'ulturists (leaf gatherers) in the foreground, Loni hardy, 
Italy. By this method of pruning, tall trunks from 8 to 10 feet from 
the ground are produced, necessitating the use of ladders for leaf gath- 
ering. From a i)hotograph taken August 2(>. 1002, hy Dr. L. O. Howard. 
Plate I. Branch of the white mulberry, ^[onl.•< alha. with large undivided leaves, 
of thick texture and smooth surface. The leaves nf this variety are pre- 
eminently adai)ted for silkworm food. From photograph of a tree in 
the grounds of the I\ S. Department of .\griculture. 
II. r>ranch of seedling white mulberry, Morux dlbo, with divided leaves. Seed- 
lings from the same parent will sometimes have leaves of the divided 
form, others assuming the undivided shape shown in Plate I, while some 
may have both forms on the same tree. 
III. An ornamental variety of nuill>erry, .][nrii.<! aHm, variety rrnosa. Of no 

value as food for silkworms. 
lY. Leaves of seedling Russian mulberry, .^fnrns aJhn, variety tntarici. This 
nuilberry, owing to its extremi' hardiness, is used for stocks on which to 
graft or bud the most valuable varieties in order to perpetuate their 
characteristics, i)ropagation from seed l)eing altogether unreliable for 
perpetuating varieties. 
Y. The native red mulberry. Moms ruhrn. From a specimen in the Herbarium 
of the T'. S. National ]\Iuseinii. The varieties of this species are usually 
jtrized for their fruits, being of little value as food for silkworms. 
YI. Paper mull )eiTy, Jh-onsxonetia ])aj))/yif< m. Valueless in silk culture. A. — 
Leaf from old tree. B.— Leaf from 2-year-old seedling. C— Twig with 
female flowers. 
YII. The Persian or black mulberry, Morns nigra. This species is cultivated in 
Furope and Asia for its fruit. From photograph of a tree in the grounds 
of the r. S. Department of Agriculture. 
YIII. Osage orange, To.ri/lon jiomifervm. Leaves, fruit, and l)ark. The mature 
leaves of this native tree provide excellent food for silkworms. 
IX. Sununer cuttings of the white mulberry, with leaves sliortened to prevent 
excessive evaporation. 
X. Winter cuttings of 1-year old shoots of white nuilberi-y, ready for planting. 
XL Hoot grafting the mulberry. A and B.— Scions fitted on stocks, ready to 
be tied. C. — Stock and scion \\ rajjited and ready to be jjlanted. 
XII. St'ion or sprig budding. This method of i>ropagation can be used on 
strong seedling stocks or on branches of trees. A and B. — Scions pre- 
pared for inserting. C. — Stock with bark raised, ready for scion. D. — 
Scion in position, ready to be wrapped. E. — Stock with scion held in 
l^lace by wrapping. F. — Stock waxed to exclude air and moisture. 
20 





34, Bureau of Plant Industry, U. S. Dept. of Agncultun 




Branch of White Mulberry (Morus albai, with Large Undivided Leaves. 



34, Bureau of Plant Industry, U. S. Dept. of Agri 



Plate II. 




Branch of White Mulberry iMorus alba', with Divided Leaves. 



34, Bureau of Plant Industry, U. S. Dept. of Agriculture. 




Branch of White Mulberry <Morus alba', Variety venosa. 



34, Bureau of Plant Industry, U. S. Dept. of Agricultun 



Plate IV. 




Leaves of Seedling Russian Mulberry (Morus alba*, Variety tatarica. 



34, Bureau of Plant Industry, U. S. Dept. of Agriculturi 



Plate V. 




Branch of the Native Red Mulberry (Morus rubrai 



of Plant Industry, U. S. Dept. of Agri 




Bui. 34, Bureau of Plant Industry, U. S. Dept. of Agricuitu 



Plate VII. 




Branch of the Persian or Black Mulberry iMorus nigr/ 



ndustry, U. S. Dept. of Agriculture. 



Plate VIII. 




34, Bureau of Plant Industry, U. S. Dept. of Agm 




Summer Cuttings of White Mulberry, with Leaves Shortened. 



34, Bureau of Plant Industry, U, S. Dept. of Agriculture. 



Plate X. 




Winter Cuttings of One-year-old Shoots of White Mulberry, Ready for Plantinc 



34, Bureau of Plant Industry, U. S Dept. of Agriculture. 




Root Grafting the Mulberry. 

A and K, sciuns tiltiMl (iii stdcks, rca.ly I., he tied; C, stock and scion wrapped and ready (o l,c planted. 



Bui, 34, 



I of Plant Industry, U. S. Dept. of Agr 



Plate XII. 




LIBRARY 



OF CONGRESS 



002 849 355 1 % 



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